Mechanical Properties of Silicon Carbide Nanowires: Effect of Size-Dependent Defect Density
Mechanical Properties of Silicon Carbide Nanowires: Effect of Size-Dependent Defect Density
复制标题
DOI：
10.1021/nl404058r
复制
发表时间：
2014-02-01
期刊：
影响因子：
10.8
通讯作者：
Zhu, Yong
中科院分区：
文献类型：
--
作者：
Cheng, Guangming;Chang, Tzu-Hsuan;Zhu, Yong
本文报道了利用微电子机械系统在扫描电子显微镜内进行原位拉伸测试，对碳化硅纳米线(NWS)的力学性能进行了定量表征。采用气-液-固法合成了晶向为<；111>；的纳米晶。它们由三种结构组成：纯面心立方(3C)结构、倾斜层错(SF)3C结构和高度缺陷结构，沿NW向呈周期性变化。发现碳化硅纳米管呈线弹性形变，直至脆性断裂。断口来源是倾斜SFS的3C结构，而不是高度缺陷的结构。断裂强度随NW直径从45 nm减小到17 nm而增加，接近3C-SiC的理论强度。尺寸效应对碳化硅纳米管断裂强度的影响主要归因于尺寸相关的缺陷密度，而不是单晶纳米管的主要表面效应。
This paper reports quantitative mechanical characterization of silicon carbide (SiC) nanowires (NWs) via in situ tensile tests inside scanning electron microscopy using a microelectromechanical system. The NWs are synthesized using the vapor liquid solid process with growth direction of < 111 >. They consist of three types of structures, pure face-centered cubic (3C) structure, 3C structure with an inclined stacking fault (SF), and highly defective structure, in a periodic fashion along the NW length. The SiC NWs are found to deform linear elastically until brittle fracture. Their fracture origin is identified in the 3C structures with inclined SFs, rather than the highly defective structures. The fracture strength increases as the NW diameter decreases from 45 to 17 nm, approaching the theoretical strength of 3C SiC. The size effect on fracture strength of SiC NWs is attributed to the size-dependent defect density rather than the surface effect that is dominant for single crystalline NWs.